Why Do Magnets Ruin Credit Cards?

The strip on the back of your credit card is made up of magnetic particles that contain the account information. Any contact with a magnet or magnetic field can cause the strip to become demagnetized and the card to be ruined. Exposure to magnets can cause the particles in the strip to rearrange, making the card unreadable.

Function of the Magnetic Strip

The credit card reader at a merchant picks up the account information when your card is swiped. This information includes your account number, account holder name, account balance, expiration date and account limitations. If your card’s strip has had it particles rearranged, the card reader will be unable to read any information from the card. This will prevent you from being able to use your card even if your account is valid.

Ways Magnetic Strips Are Damaged

Exposure to any external magnet or magnetic field can demagnetize your credit card. Credit cards can be ruined when they come into contact with a refrigerator door magnet, purse magnet or wallet magnet. If your credit card magnetic strip is placed against another card’s strip, both cards can be ruined. Credit cards can also be demagnetized by the security deactivation devices found at checkouts. These devices are the pads that cashiers run certain items over before bagging.

What to do if the Magnetic Strip is Damaged

Once your credit card is demagnetized there is no way to fix the card. If your card is demagnetized you will need to call your credit card company to request a new card. If your credit card strip has been ruined, the merchant can call in for a manual authorization for your purchase. However, since a demagnetized strip can be a sign of a fake or stolen card, some merchants are unwilling to call for a manual authorization. Once you receive the new card your old card should be cut up or shredded and thrown away.


You can prevent your credit cards from being ruined. When placing cards near each other in your wallet, make sure the strips do not touch. If a store uses security deactivation devices at the register, do not set your purse, wallet or card near the pad. When going for medical tests, keep your purse or wallet away from the machines.


Having a credit card ruined is frustrating but knowing how it can happen can be a benefit. Before you throw away expired or unwanted cards, demagnetize them with a magnet at home. This will prevent anyone else from using your credit card to steal your identity. Even a credit card that has been cut up can still be used by a knowledgeable thief if the strip has not been demagnetized.